The Separation And The Study On The Bio-Flocculant Specificity Of Microbial Bio-Flocculant Bacterium

Floccuant is the most important water treating agent which can result in removeing of the suspended solid in water.The traditional inorganic flocculants are used largely in practical water treatments, but they are easily to result in secondary pollution.The flocculant of organic polymer, especially polyacrylamide, are not easily to be degraded, and its residual in water body can have toxical effects on animals who consume such water. With the development and enhancement of bio-technology and environmental protection consciousness, a kind of natural high polymer flocculant with security, highly effective and no secondary pollution is the hot subject for studying and developing.The thesis carried on the comprehensive summary for the flocculant classification, the characteristic, the application and the recent research, especially for the bioflocculant characteristic, the research development and the application. Based one this, it is clear that the key problem in the bio-floccuant developing is getting the effective strains, understanding the growrh conditions of strains and droping down the cost of bio-floccuant. So all of these points are the contents of this thesis.Effective strains were isorated from the samples of active sludge, the sewage and the soil. Three effective strains were isolated from these samples. They are NⅠ7, NⅡ4, and NⅢ2. Detailed studies had been carried on the growth of cycle, the growth condition, the active ingredient distribution and thermostability of boil-flocculant of these strains. At the same time, the influence factor and application of floccutants produced by our strains were also studied. The bio-flocculant production cost was estimated in the paper.The results showed that three bacterium strains produced extracelluar flocculant accompany with their growth. The most suitable carbon source in culture medium for the three strains is as: ethyl alcohol for NⅠ7strain, glucose for NⅡ4 and NⅢ2. The most suitable nitrogen source in culture mediumfor the three strains: ammonium sulfate for NI7 and NII4, the urea for NIII2. The experinmental results showed that: the best pH values of culture medium are 7~8;the bio-flocculant produced by strain NI7 and NIII2 was still high after heating 20min in water SO'C—SO'C, but the bio-flocculant activity produced by strain NII4 drop rapidly after heating 20min in water 80 °C;in using our bio-flocculant, the best pH value of water samples is 8-12, the suitable amount of the bio-flocculant produced by NI7n NII4 and MII2 are 2> 2and 3ml/( 100ml water sample), under this conditions the highest removing rates of suspended solid of water samples (contain 5g/L kaolin clay) are 90%;positive ion can promote the flocculation activity of bio-flocculant and Ca2+is the most effective, the suitable adding amount of 1% CaCk solution is 3.5~5ml/( in 100ml water sample). The bio-flocculant produced by the three strains have good flocculating effect on water from Wei He river, but less effective on water from sewage. The treating cost by using our bio-flocculant will be $ 2.30612 -2.63558 per- ton-wastewater.The thesis have made a lot of foundation studing on the bio-flocculant developing. The results will provide value reference for bio-flocculant application.